The analog TV bands include the Very High Frequency (VHF) band and the Ultra High Frequency (UHF) band. The VHF is composed of the low VHF band operating from 54 MHz to 88 MHz (excluding 72 MHz to 76 MHz), and the high VHF band operating from 174 MHz to 216 MHz. The UHF band is composed of the low UHF band operating from 470 MHz to 698 MHz, and the high UHF band operating from 698 MHz to 806 MHz. Within the TV bands, each TV channel has 6 MHz bandwidth. Channels 2 to 6 are in the low VHF band; Channels 7 to 13 are in the high VHF band; Channels 14-51 are in the low UHF band; Channels 52 to 69 are in the high UHF band.
In the United States, the Federal Communications Commission (FCC) set Jun. 12, 2009 as the deadline for replacing analog TV broadcasting by digital TV broadcasting. The digital TV channel definitions are the same as the analog TV channel. The digital TV bands use analog TV channels 2 to 51 (except 37), while the analog TV channels 52 to 69 may be used for new non-broadcast users. The frequency allocated to a broadcasting service but not used locally is called White Space (WS). The TVWS refers to the TV channels 2 to 51 (except 37).
Besides TV signals, there are other licensed signals transmitted on the TV bands. Channel 37 is reserved for radio astronomy and Wireless Medical Telemetry Service (WMTS), where the latter may operate on any vacant TV channels 7 to 46. Private Land Mobile Radio System (PLMRS) uses channels 14 to 20 in certain metropolitan areas. Remote control devices use any channels above channel 4, except channel 37. The starting frequency of FM channel 200 is 87.9 MHz, with partial overlapping on TV channel 6. The wireless microphone uses channels 2 to 51 with a bandwidth of 200 kHz. The FCC has ruled that the wireless microphone usage is restricted to two pre-specified channels, and its operation on other channels requires a pre-registry.
Because of the transition from analog to digital TV transmissions in the 470-862 MHz frequency band, certain portions of the spectrum are no longer used for TV transmissions, though the amount and exact frequency of unused spectrum varies from location to location. The FCC has opened up these TVWS frequencies for a variety of unlicensed uses.